This invention is related to a kind of transient voltage suppressor structure, especially to a transient voltage suppressor structure that prevents the tip on the edge of the signal electrode from contacting with functional material by using an insulation layer.
The transient voltage suppressors developed in recent years feature the embedment of a variable impedance material in their structure through which the signal electrode and the ground electrode are connected electrically. The characteristics of these variable impedance material lie in that they can change their impedance in an appropriate range of voltage. When the signal electrode is in the range of normal working voltage, the variable impedance material is in a state of high impedance, so that the voltage and current on the signal electrode in the range of normal working voltage can work appropriately and will not be conducted to the ground electrode. However, when abnormal pulse appears on the signal electrode, the variable impedance materials is shifted to a low impedance state and the energy of the pulse is conducted from the signal electrode to the ground electrode through a transient voltage suppressor and released from the ground electrode. Therefore, the voltage of the signal electrode is limited within an allowable range so that circuits can be protected through the characteristics of the variable impedance material.
There are various kinds of transient voltage suppressors that are conventionally made from variable impedance material, among which the voltage suppressor with a single layer structure is generally applied in the industry. The voltage suppressor with such structure usually has a larger volume and can sustain extreme pulse energy, such as lightning. Another voltage suppressor structure used in the industry is multi-layer structure that has a smaller volume and formed to be a surface adhesion type.
Please refer to FIG. 1. The conventional voltage suppressor structure usually has a basic substrate 100 as its matrix on which there is a signal electrode 202a, a variable impedance material 104 and a ground electrode 202b. Part of the variable impedance material 104 covers the basic substrate 100 and the rest part of it covers the signal electrode 202a, while part of the ground electrode 202b covers the basic substrate 100 and the rest part of it covers the variable impedance material 104 to form a stacked structure.
Please refer to FIG. 2. The voltage suppressor structure protected by U.S. Pat. No. 6,013,358 has a glass or ceramic basic substrate as its matrix. The density of this glass or ceramic plat 200 exceeds 3.5 g/cm3 and has a pair of electrodes 202, including a signal electrode 202a and a ground electrode 202b. A variable impedance material 204 is placed between the signal electrode 202a and the ground electrode 202b. It covers the basic substrate 100 and a part of the signal electrode 202a and ground electrode 202b, so that the transient voltage can be conducted from the signal electrode 202a to the ground electrode 202b and released from the latter.
Please refer to FIG. 3. No matter whether the thin or thick film technology is applied, the thickness on the edge of the signal electrode 102a becomes thin gradually when the signal electrode 102a is formed and an included angle between the tangent of the signal electrode 102a and the horizontal line appears in a form of an acute angle. This acute angle produces point discharge easily when transient voltage appears and the energy concentrates itself for this discharge. As a result, the capability of the voltage suppressor to sustain transient voltage is restricted and affects the performance of the whole suppressor.
Therefore, the purpose of the said invention is to provide a kind of transient voltage suppressor structure that insulates the edge of the signal electrode from the variable impedance material with an insulator to remove the point discharge of the signal electrode in the transient voltage suppressor structure and increase the capability of the suppressor to sustain transient voltage.
The purpose of the said invention is to provide a kind of transient voltage suppressor structure that insulates the edge of the signal electrode from the variable impedance material with an insulator. In this way, the pulse energy is forced to distribute over the contact face of the signal electrode and the variable impedance material without concentrating onto the small area on the edge of the electrode and causing damage to the material.
A transient voltage suppressor structure is provided to accomplish the purpose of the said invention. An insulation layer is used in this structure to prevent the edge of the signal electrode from contacting with the variable impedance material and, further, remove the effect of the point discharge existing on the edge of the signal electrode. No matter whether the thin or thick film technology is applied, the thickness on the edge of the signal electrode becomes thin gradually when the signal electrode is formed and an included angle between the tangent of the signal electrode and the horizontal line appears in a form of an acute angle. This acute angle produces point discharge easily when transient voltage appears and the energy concentrates itself for this discharge. As a result, the capability of the voltage suppressor to sustain transient voltage is restricted. The said invention is a structure that insulates the edge of the signal electrode from the variable impedance material with an insulator to increase the capability of the transient voltage suppressor to sustain transient voltage.
To easily understand the purposes, characteristics and advantages of the said invention, a preferred embodiment with figures is described in detail as follows: